KR100889147B1 - Mid-range vinylidene content polyisobutylene and production thereof - Google Patents

Abstract

A relatively low molecular weight, mid-range vinylidene content PIB polymer product and a process for making the same. At least about 90 % of the PIB molecules present in the product comprise alpha or beta position isomers. The vinylidene (alpha) isomer content of the product may range from 20 % to 70 % thereof and the content of tetra-substituted internal double bonds is very low, preferably less than about 5 % and ideally less than about 1-2 %. The mid-range vinylidene content PIB polymer products are prepared by a liquid phase polymerization process conducted in a loop reactor (10,100) at a temperature of at least 60 °F using a BF 3 /methanol catalyst complex and a contact time of no more than 4 minutes.

Description

Mid-range vinylidene content polyisobutylene and its preparation {MID-RANGE VINYLIDENE CONTENT POLYISOBUTYLENE AND PRODUCTION THEREOF}

The present invention relates to the production of polyisobutylene (PIB). In particular, the present invention relates to the preparation of PIB compositions of mid-range vinylidene content. In this regard, the present invention provides a novel liquid phase process for the polymerization of isobutylene to prepare mid-range vinylidene content PIB compositions using a modified BF ₃ catalyst. The present invention also provides new compositions of matter comprising PIB compositions of medium-range vinylidene content.

Polymerization of isobutylene using Friedel-Crafts type catalysts, including BF ₃ , is a commonly known method, for example, "HIGH POLYMERS", Vol. XXIV (J. Wiley & Sons, Inc., New York, 1971), pp. 713 ff. The degree of polymerization of the resulting product varies with many known polymerization reaction techniques used. In the latter case, it is generally recognized that the molecular weight of the polymer product is directly related to the degree of polymerization.

It is also known that PIBs can be made of at least two different major grades-regular and high vinylidene. Typically, these two product grades are made in different ways, but both often use dilute isobutylene feedstock with an isobutylene concentration in the range of 40-60% by weight. Recently, it has been known that at least high vinylidene PIB can be produced using concentrated feedstock having an isobutylene content of at least 90% by weight. Non-reactive hydrocarbons, such as isobutane, n-butane and / or other lower alkanes, which are generally present in petroleum fractions, may also be included in the feedstock as diluents. In addition, the feedstock may often contain small amounts of other unsaturated hydrocarbons such as 1-butene and 2-butene.

Usually grades PIB can range in molecular weight from 500 to 1,000,000 or more, and are generally prepared in batch processes at low temperatures (sometimes as low as -50 to -70 ° C). The catalyst is generally not completely removed from the final PIB product due to process specificities. Since the molecular weight of the product changes inversely with temperature, the molecular weight can be controlled with temperature. That is, the higher the temperature, the lower the molecular weight. The reaction time is often several hours. The desired polymer product has one double bond per molecule, and the double bond is mostly present inside. Generally speaking, at least about 90% of the double bonds are internal and less than 10% of the double bonds are in the terminal position. Although it is believed that the formation of terminal double bonds is favored kinematically, both the long reaction time and the fact that the catalyst is not completely removed promote the rearrangement of the molecules to form more thermodynamically advantageous internal double bond isomers. Regular PIBs can be used, in particular, as viscosity modifiers in lubricating oils, as thickeners, and as tackifiers for plastic films and adhesives. PIB can also function as an intermediate for the preparation of detergents and dispersants for fuels and lubricants.

High vinylidene PIB, a relatively new commodity on the market, can be characterized by a high percentage of terminal double bonds, typically higher than 70% and preferably higher than 80%. As this usually provides a better reactive product compared to PIB, this product is also called high reactive PIB. The terms high reactivity (HR-PIB) and high vinylidene (HV-PIB) are synonymous. All of the basic processes for preparing HV-PIB are reactor systems using BF ₃ and / or modified BF ₃ catalysts, in which the reaction time can be precisely controlled and the catalyst can be neutralized immediately once the desired product is formed. Include. Since the formation of terminal double bonds is kinematically advantageous, short reaction times favor high vinylidene levels. The reaction is generally terminated with an aqueous base solution, for example NH ₄ OH, before a significant isomerization reaction of the internal double bond can occur. The molecular weight is relatively low. As used in this application, the term "relatively low" refers to a number average molecular weight (M _N ) of less than about 10,000. HV-PIB with M _N of about 950-1050 is the most common product. Attempts to advance the reaction to higher conversions reduce the vinylidene content through isomerization, so conversion based on isobutylene is maintained at 75-85%. Prior US Patents 4,152,499 dated May 1, 1979, 4,605,808 dated August 12, 1986, 5,068,490 dated 26 November 1991, 5,191,044 dated March 2, 1993, June 22, 1992 5,286,823, 5,408,018 dated April 18, 1995, and 5,962,604 dated October 5, 1999, directly relate to this material.

US Pat. No. 4,152,499 describes a process for the production of PIBs from isobutylene under a gaseous BF ₃ blanket which acts as a polymerization catalyst. The method results in PIB with 60-90% of the double bonds at the terminal (vinylidene) positions.

U.S. Patent 4,605,808 discloses a process for the production of PIB using a catalyst consisting of a complex of BF ₃ and an alcohol. The use of such catalyst complexes is proposed to allow more effective control of the reaction parameters. A reaction contact time of at least 8 minutes is required to obtain the PIB product, and at least about 70% of the double bonds are present at the terminal positions.

U.S. Patent 5,191,044 discloses a process for preparing PIB which requires delicate pretreatment of BF ₃ / alcohol complexes to ensure that all free BF ₃ is not present in the reactor. The complex must contain excess alcohol complexing agent to obtain a product in which at least about 70% of the double bond is at the terminal position. The only illustrated reaction time is 10 minutes and the reaction is carried out at temperatures below 0 ° C.

In addition to precise control of the reaction time, a way to obtain high vinylidene levels seems to be control of the catalytic reactivity. This has been done in the past by complexing BF ₃ with various oxygenates, including sec-butanol and MTBE. One theory is that these complexes are in fact less reactive than BF ₃ itself and unevenly slow down the isomerization reaction, which results in a greater difference between the vinylidene formation reaction (polymerization reaction) and the isomerization reaction rate. In addition, a mechanism has been proposed that the BF ₃ complex cannot non-isomerize terminal double bonds by non-protonation. This further suggests that water (preferably capable of protonating BF ₃ ) should generally be excluded from this reaction. Indeed, prior literature describing the production of PIB using BF ₃ complexes is known that low moisture feedstocks (up to 20 ppm) are critical for the formation of high vinylidene products.

HV-PIBs are increasingly replacing medium grade PIBs for intermediate production due to their higher reactivity as well as the need for development of "chloride free" materials in the application of the final product. Important PIB derivatives are PIB amines, PIB alkylates and PIB maleic anhydride adducts.

PIB amines can be prepared using a variety of methods involving other PIB intermediates that provide reaction sites for subsequent amination. These intermediates may include, for example, epoxides, halides, maleic anhydride adducts, carbonyl derivatives.

Reference to HV-PIB as "highly reactive" is relative to the grade of PIB. HV-PIB, in the strict sense, is still not highly reactive towards forming some of these intermediates. Other types of compounds, polyethers, may have higher reactivity, for example in the formation of amines and amine intermediates. Amines derived from polyethers are known as polyether amines (PEA's) and are competition products for PIB amines.

The use of HV-PIB as alkylating agent of phenolic compounds is caused by the high reactivity and high yield that can be achieved with HV-PIB. These very long alkyl phenols are good hydrophobes for surfactants and similar products.

The largest amount of PIB derivative is the PIB-maleic anhydride reaction product. HV-PIB reacts with maleic anhydride through a double bond to give a product with anhydride functionality. This functionality provides the reactivity for the formation of amines and other carboxylate derivatives. These products are the base material for most lubricant cleansers and dispersants produced today. As mentioned above, PIB-maleic anhydride products are also used as intermediates in the production of PIB amine fuel additives.

More recently, new and more valuable processes have been developed for the efficient and economical production of HV-PIB. This new process was filed on January 29, 2000, and is described in US patent application Ser. No. 09 / 515,790 (hereinafter referred to as the '790 application'), which is common to the present applicant and the applicant. The entire disclosure of the '790 application is specifically incorporated herein by reference.

The '790 application relates to an HV-PIB production process in which the polymerization reaction takes place at higher temperatures and lower reaction times than previously thought possible. In particular, the '790 application describes a liquid phase polymerization process for producing low molecular weight, high reactivity polyisobutylene. Roughly stated, the process of the '790 application may include cationic polymerization reactions. However, under some conditions the polymerization may be covalent. In particular, the latter may be true when ether is used as the complexing agent. According to the disclosure of the '790 application, the process comprises providing a catalyst composition comprising a BF ₃ complex and a complexing agent and a feedstock comprising isobutylene. The feedstock and catalyst composition are introduced into the remaining reaction mixture in the reaction zone individually or as a single mixed stream. The remaining reaction mixture, feedstock and catalyst composition are then thoroughly mixed together to provide a thoroughly mixed mixture within the reaction zone. While in the reaction zone, the reaction mixture is maintained in thoroughly intermixed conditions and at a temperature of at least about 0 ° C. such that isobutylene in the reaction mixture undergoes a polymerization reaction to form a polyisobutylene product. . The product stream comprising low molecular weight, highly reactive polyisobutylene is then recovered from the reaction zone. The introduction of the feedstock into the reaction zone and the recovery of the product flow from the reaction zone are controlled such that the residence time of the isobutylene polymerized in the reaction zone does not exceed about 4 minutes. According to the '790 application, the reaction can be carried out such that the residence time is about 3 minutes or less, about 2 minutes or less, about 1 minute or less, and ideally much less than 1 minute.

"According to the concepts and principles disclosed in the 790 application, the process is generated polyisobutylene of about 350 to range from about 5000 M _N, of an M _N in the range of about 600 to about 4000, from about 700 to about 3000 range M _N, in the range of about 800 to 2000 M _N, and ideally may be performed so as to have an M _N in the range of about 950 to 1050. Moreover, the process can be controlled such that a particular M _N , for example about 1000 M _N , can be achieved.

As such, the '790 application discloses a process that can be sufficiently controlled to ensure the production of polyisobutylene products having a vinylidene content of at least about 70%. More preferably, the PIB product may have a vinylidene content of at least about 80%. In fact, by adopting the presentation of the '790 application, a vinylidene content of at least about 90% can be readily achieved.

As described in the '790 application, the complexing agent used to complex the BF ₃ catalyst may suitably be an alcohol, preferably a primary alcohol. More preferably the complexing agent may consist of C ₁ -C ₈ primary alcohols, ideally methanol.

To obtain the most desirable results according to the presentation of the '790 application, the molar ratio of BF ₃ to the complexing agent in the complex may range from about 0.5: 1 to about 5: 1. Preferably, the molar ratio of BF ₃ to the complexing agent in the complex may range from about 0.5: 1 to about 2: 1. More preferably, the molar ratio of BF ₃ to the complexing agent in the complex may range from about 0.5: 1 to about 1: 1, and ideally, the molar ratio of BF ₃ to the complexing agent in the complex is about May be 1: 1.

According to a further application of the '790 application, for each mole of isobutylene introduced into the mixture in the feedstock, from about 0.1 to about 10 millimoles of BF ₃ can be introduced into the reaction mixture together with the catalyst composition. desirable. More preferably, for each mole of isobutylene introduced into the mixture in the feedstock, from about 0.5 to about 2 millimoles of BF ₃ may be introduced into the reaction mixture along with the catalyst composition.

When the presentation of the '790 application is applied, the polydispersity of the resulting polyisobutylene may be about 2.0 or less, and preferably about 1.65 or less. Ideally, polydispersity may range from about 1.3 to about 1.5.

According to one preferred embodiment set forth in the '790 application, the reaction zone may comprise a loop reactor in which the reaction mixture is continuously recycled at a first volume flow rate and the feedstock and catalyst composition Can be introduced continuously at the combined second volume flow rate. The ratio of the first volume flow rate to the second volume flow rate may suitably range from about 20: 1 to about 50: 1, preferably from about 25: 1 to about 40: 1. And ideally range from about 28: 1 to about 35: 1. In order to obtain the preferred advantages of the loop reactor, the ratio of the first volume flow rate to the second volume flow rate is preferably such that the component concentration in the reaction mixture is substantially constant, and / or substantially isothermal conditions are reacted. To be established and maintained in the mixture.

As described in the '790 application, the feedstock and catalyst composition may be premixed and introduced together into the reaction zone as a single stream at a second volume flow rate. Alternatively, the feedstock and catalyst composition are introduced separately into the reaction zone as two separate streams, the sum of their flow rates being the second volume flow rate.

In order to achieve the ideal results described in the '790 application, the reactor configuration, the properties of the reaction mixture and the first volume flow rate may allow turbulent flow to be maintained within the reaction zone. In particular, the system may allow at least about 2000 Reynolds numbers to be achieved and maintained within the reaction zone. In addition, the system may allow a heat transfer coefficient U of at least about 50 Btu / min ft ² ° F to be achieved and maintained in the reaction zone. For this purpose, the reactor may preferably be the tube side of a shell-and-tube heat exchanger.

According to additional concepts and principles of the novel process described in the '790 application, the feedstock generally comprises at least about 30 weight percent isobutylene and the balance may be a non-reactive hydrocarbon diluent.

As mentioned above, high vinylidene PIB contains only one double bond in each molecule, most of which are located at the terminal (alpha). Typically at least 70, and preferably at least 80% of the double bonds are at the terminal (alpha). In general, in known high vinylidene PIB products, the remaining 20-30% of the double bonds are in the beta position (between the second and third carbons of the polymer backbone). These beta position double bonds can be either 1,1,2-trisubstituted or 1,2,2-trisubstituted. Tetra-substituted isomers are rarely present in high vinylidene PIBs prepared according to the '790 application, so the total sum of alpha and beta isomers is substantially about 100%.

On the other hand, the normal (normal) PIB also contains only one double bond per molecule, but only about 5-10% of these double bonds are in the alpha position and only about 50% are in the beta position. The remainder of the PIB isomer is tetra-substituted and includes double bonds present inside the polymer as a result of the isomerization reaction occurring during preparation. Due to the relatively high level of non-reactive tetra-substituted olefin content, these products are sometimes referred to as low reactivity PIB.

In the past, only known PIB compositions contained (1) highly reactive PIBs containing substantially 100% of alpha and beta olefin isomers, having (a) vinylidene (alpha) isomer content of greater than 70%, and (2) alpha and It is a low reactivity PIB having a beta isomer content of about 60% and a vinylidene (alpha) content of less than about 10%.

Summary of the Invention

The present invention provides a novel, relatively low molecular weight, mid-range vinylidene content PIB polymer product and a process for preparing the product. The alpha (vinylidene) position PIB isomers and beta position PIB isomers present in the mid-range vinylidene content PIB polymer product preferably comprise at least about 90% of the total molecules present in the product. Preferably, the alpha and beta isomers may comprise at least about 95% of the total molecules present in the product, and ideally the alpha and beta isomers will comprise substantially 100% of the total molecules present in the product. Can be. In general, according to the concepts and principles of the present invention, the vinylidene (alpha) isomer content of the product may be less than 70% of it, and may be as low as 20%. Conversely, the beta isomeric content may range from about 30% to about 80% of the total molecules present in the product. In the mid-range vinylidene content PIB compositions of the present invention, the content of tetra-substituted internal double bonds is suitably very low, advantageously less than about 10%, preferably less than about 5%, ideally Is less than about 1-2% of the double bond. The advantage of these products is that for some applications their overall reactivity is very high without the need for vinylidene content.

Detailed Description of the Preferred Embodiments

As mentioned above, a new methodology for preparing high vinylidene PIB polymers (> 70% alpha position double bonds) is described in the '790 application, the entire disclosure of which is incorporated by reference herein. In accordance with the concepts and principles of the present invention, the process parameters described in the '790 application may be manipulated and / or adjusted to provide the conditions necessary to produce mid-range vinylidene content PIB compositions. In preparing the desired mid-range content vinylidene PIB of the present invention, the vinylidene (alpha position double bond) isomer content can range from about 20% to about 70%, and the process parameters disclosed in the '790 application are as follows: Can be manipulated as:

(1) The ratio of catalyst complexing agent to BF ₃ in the catalyst complex of 1.3: 1 or less is preferably employed, with higher amounts of BF ₃ and correspondingly lower amounts of catalyst in the catalyst complex The presence of complexing agents results in reduced catalyst consumption;

(2) For a given M _N , higher reaction temperatures may be used. For M _{N on} the order of about 1050, the temperature reasonably corresponds to about 90 ° F., while typical reaction temperatures on the order of 60 ° F. are preferred for producing high vinylidene products;

(3) the reaction time can be reasonably kept to a minimum, preferably less than 4 minutes, and ideally less than 1 minute; And

(4) The ratio of BF ₃ to isobutylene feedstock, reactor configuration, residence time, catalyst concentration, Reynolds number, U factor, volume flow rate range, feedstock concentration, and M _N range are reasonably May be substantially the same as disclosed in the '790 application.

The polydispersity of the mid-range vinylidene content PIB products prepared as described above will tend to be narrower than the polydispersity of the highly reactive PIB produced according to the process of the '790 application due to low catalyst consumption. . Furthermore, when mid-range vinylidene content PIB products are prepared using the conditions described above, beta olefin isomers (1,1,2-trisubstituted or 1,2,2-substituted) present in the final PIB polymer composition Trisubstituted) and the total amount of alpha isomers present in the resulting PIB polymer composition amounts to almost 100% of the composition.

Mid-range vinylidene content PIB products produced using the concepts and principles of the present invention can be used in place of the highly reactive PIB products described in the '790 application as a whole for many end-use applications. Although the reaction rates may be slightly to moderately lower than with high vinylidene products, mid-range vinylidene content PIB polymer compositions are substantially 100% alpha olefin isomers and beta olefin isomers. The overall conversion is about the same because the presence of the internal double bond isomers is minimized by including.

In addition to PIB amine derivatives and PIB-maleic anhydride reaction products, the mid-range vinylidene content PIB olefin compositions of the present invention also exhibit effective reactivity in end-use such as PIB alkylation onto aromatic ring (particularly phenol) compounds. It was observed to have. Tetra-substituted internal double bonds are not reactive in the formation of the aforementioned PIB derivatives, while beta position double bonds are reactive.

Reasonably, the content of tetra-substituted internal double bond isomers of the mid-range vinylidene content PIB products of the present invention will be very low, typically up to about 1-2%, in order to optimize the performance of the product. However, the amount of tetra-substituted internal double isomers that may be acceptable in valuable commercial products may be as high as 5%.

As mentioned above, the present invention provides an improved liquid phase process for the efficient and economical preparation of mid-range vinylidene content PIB products. The present invention also provides novel mid-range vinylidene content PIB products. According to the invention, the isobutylene-containing feedstock stream is contacted with a catalyst which promotes the polymerization reaction in the reaction zone. Suitable reaction conditions as described above are provided in the reaction zone. After an appropriate residence time, the PIB-containing product stream is recovered from the reaction zone. With this in mind, the present invention can be easily controlled and manipulated as described above to provide an efficient and economical way to provide PIB products of relatively low molecular weight, mid-range vinylidene content.

The improved process of the present invention is preferably characterized by the use of a BF ₃ catalyst capable of forming a complex with a complexing agent that suitably alters the performance of the catalyst. Many other potentially useful catalysts are well known to those skilled in the art. In particular, many useful catalysts are described in the aforementioned prior patents. The complexing agent for the catalyst, in particular the BF ₃ catalyst, can be any compound containing lone pair of electrons, such as, for example, alcohols, esters or amines. However, for the purposes of the present invention the complexing agent is preferably an alcohol, suitably a primary alcohol, more suitably a C ₁ -C ₈ primary alcohol, ideally methanol.

As mentioned above, for the purposes of the present invention, the molar ratio of complexing agent to BF ₃ in the catalyst composition is generally about 1.3: 1 or less, for example about 1.2: 1 or less, about 1.1 : 1 or less, 1: 1 or less, and in fact the catalyst composition consists of BF ₃ which is substantially free of complexes for any particular application. In determining the ratio, important considerations include avoiding free BF ₃ in the reactor and minimizing tetra substituted internal double bond isomers in the product. If high molecular weight products are desired, temperatures as low as 0 ° F. are suitable, but the temperature in the reaction zone is generally and preferably higher than 60 ° F., ideally about 90 ° F. The reactor residence time may be generally and preferably less than 4 minutes, ideally less than 1 minute. Using these parameters, it is possible to operate the process to achieve a relatively low molecular weight, mid-range vinylidene content PIB product, which was not previously thought possible. According to the present invention, catalyst concentrations and BF ₃ / complexing agent ratios are generally used to achieve the desired relatively low molecular weight, medium-range vinylidene content PIB product with reaction temperatures higher than 60 ° F. and reactor residence time of less than 4 minutes. It can be manipulated to be necessary. In general, the amount of BF ₃ catalyst introduced into the reaction zone will range from about 0.1 to about 10 millimoles per mole of isobutylene introduced into the reaction zone. Preferably, the BF ₃ catalyst may be introduced at a rate of about 0.5 to about 2 millimoles per mole of isobutylene introduced into the feedstock.

The process itself consequently comprises the step of intimate mixing of the isobutylene-containing reactant stream and catalyst complex and / or removing heat during the reaction process. Tight mixing can be achieved by reasonably turbulent flow. Turbulence also enhances heat removal. These conditions, individually or together, result in higher operating temperatures (eg,> 60 ° F.) and shorter reactor residence times (eg, desired to produce relatively low molecular weight, mid-range vinylidene content PIB products). <4 minutes). These important parameters can be achieved by causing the catalytic reaction to occur in the tube of the cylindrical tubular heat exchanger at the flow rate resulting in turbulence.

Many potentially valuable reactors are well known to those skilled in the art. However, for the purposes of one preferred embodiment of the present invention, the reactor 10 may be a four pass cylindrical tubular heat exchanger, as shown in FIG. 1. The reactor may have, for example, 80 3 / 8-inch tubes having a wall thickness of 0.022 inches, each providing an inner tube diameter of 0.331 inches accordingly. The reactor has a length of 3 feet and may have internal baffling and partitions to provide four flow paths with 20 tubes per flow path. Such a configuration is well known in the heat exchanger and reactor art and no further explanation is deemed necessary.

In operation, the isobutylene-containing feedstock is introduced into the reactor system, preferably via a pipe 15 adjacent the bottom head 11 of the reactor 10. The pipe 15 directs the feedstock into the suction line 20 of the recycle pump 25. The catalyst complex is injected into the reactor recycle system through a pipe 30 adjacent the bottom head of the reactor 10. In accordance with the principles and concepts of the present invention, it should be noted that the catalyst complexes can also be injected separately into the reactor, in which case separate catalyst pumps may be required.

A catalyst modifier may be added to the feedstock via pipe 16 before the feedstock enters the reactor system. The preferred purpose of the modifier is to assist in controlling the vinylidene content of the PIB product. The catalyst modifier can be any compound that potentially contains lone pairs of electrons, such as alcohols, esters or amines. However, it is pointed out that when the amount of modifier is too large, the catalyst can be effectively suppressed. The feedstock containing the modifier enters the reactor system in the suction line 20 of the circulation pump 25. The catalyst complex composition enters the reactor system via line 30 at a location downstream of pump 25 and adjacent to the first pass as shown in FIG. 1. The catalyst complex is preferably a methanol / BF ₃ complex having a molar ratio of methanol to BF ₃ of about 1.3: 1 or less. The amount of modifier added via line 16 may vary from 0 to about 1 mole for each mole of BF ₃ added as a complex via line 30.

The circulation pump 25 pushes the reaction mixture into the bottom head 11 of the reactor 10 through line 35, control valve 40 and line 45. Flow meter 46 may be located on line 45 as shown. The reaction mixture moves upward through path 50, downward through path 51, upward through path 52, and downward through path 53. As described above, each pass 50, 51, 52, and 53 may preferably include a separate tube 20. For clarity, only a portion of each single tube is schematically shown in each pass in FIG. 1. These tubes are specified by member numbers 50a, 51a, 52a and 53a. However, as mentioned above, each pass consists of a plurality, for example 20, of these individual tubes, each of which extends between the top head 11 and the bottom head 12 and the head 11. Fluid communication between the head and the head 12.

The reaction mixture is preferably circulated through the tubes 50a, 51a, 52a, 53a of the reactor at a flow rate sufficient to achieve turbulent flow to achieve a heat transfer coefficient suitable for providing tight mixing and adequate cooling between the catalyst complex and the reactants. It should be noted. In this regard, the flow rate, reaction mixture properties, reaction conditions and reactor configuration can be determined in the reactor tube in the range of about 2000 to about 3000 Reynolds number (Re) and heat transfer coefficient (U) in the range of about 50 to about 150 Btu / min ft ² . It must be suitable for generating Such a parameter can generally be obtained when the linear flow rate of a typical reaction mixture, through a tube with an internal diameter of 0.331 inches, is in the range of about 6 to 9 per second.

The circulating reaction mixture exits the reactor 10 via the suction line 20. The circulating reaction mixture is preferably maintained at steady state equilibrium conditions such that the reactor is substantially a continuous stir tank reactor (CSTR). The reactor may also be of the type sometimes referred to as the loop reactor. With such a system being the only preferred system since there are a number of different arrangements that will be apparent to those skilled in the art, the flow rate of the reactant mixture in the reactor is controlled to achieve complete mixing of the catalyst mixture and reactants and proper temperature control. And independent of product removal rate.

The product outlet line 55 may preferably be provided to the upper head 12 at a point approximately adjacent the transition zone between the third and fourth passes. Such positioning is desirable to avoid the possibility of loss of unreacted isobutylene. Moreover, the positioning of the outlet line 55 would be suitable to facilitate the outflow of gas from the reactor during the start of operation. The refrigerant will preferably be circulated on the shell side of the reactor at a rate to remove heat of reaction and maintain the desired temperature in the reactor.

The product exiting the system through line 55 must be stopped immediately using a material capable of inactivating the catalyst, for example ammonium hydroxide. As such, potential rearrangements of polymer molecules that convert double bonds from desired terminal and beta positions are minimized. The relatively low molecular weight, mid-range vinylidene content PIB product of the present invention is then introduced into a work-up system (not shown), wherein the catalyst salt is removed and the PIB product is unreacted iso From other undesirable contaminants such as butylene and diluents. The latter of these can then be recycled or dedicated to other uses using known methodologies.

For the recycle system described, the feedstock introduction rate and product removal rate into the reaction mixture are each independent of the recycle rate. As will be apparent to those skilled in the art, the number of passes through the reactor and the size and configuration of the reactor are simply matters of choice. The feedstock and product recovery flow rates are preferably selected such that the residence time of the reaction mixture in the reactor is 4 minutes or less, preferably 2 minutes or less, more preferably 1 minute or less, and ideally less than 1 minute. Can be. From a commercial operation point of view, the flow rate should be such that the residence time of the reaction mixture in the reactor is in the range of about 45 to about 90 seconds. In this regard, the residence time is defined as the volume of the entire reactor system divided by the volume flow rate.

The recycle flow rate, ie, the flow rate of the reaction mixture in the system led to the recycle pump 25, is adjusted to achieve appropriate turbulence and / or heat transfer characteristics as described above. This recycle flow rate is often a function of the system itself and other desired process conditions. For the systems described above, the ratio of recycle flow rate (recycle ratio) to incoming feedstock flow rate generally ranges from about 20: 1 to about 50: 1, preferably from about 25: 1 to about 40: 1. And, ideally, in the range of about 28: 1 to about 35: 1. In particular, in addition to causing turbulence and providing an appropriate heat transfer coefficient, the recycle flow rate of the reaction mixture is substantially maintained by keeping the concentration of the components therein substantially constant and / or by minimizing the temperature gradient in the circulating reaction mixture. Isothermal conditions should be sufficient to achieve and maintain the reactor.

As mentioned above, the recycle ratio should generally range from about 20: 1 to about 50: 1. Higher recycle ratios increase the degree of mixing and allow the reactor to approach isothermal operation, leading to narrower polymer dispersions. Lower recycle ratios reduce the amount of mixing in the reactor, resulting in greater mismatch in the temperature profile. As the recycle ratio approaches zero, the design equation for the reactor becomes the design equation for the plug flow reactor model. On the other hand, as the recycle ratio approaches infinity, the modeling equation becomes the equation for CTSR. When CSTR conditions are achieved, both temperature and composition remain constant, and the composition of the product stream leaving the reactor is the same as the composition of the reaction mixture that is recycled in the reactor.

Needless to say, after equilibration has taken place, as feedstock enters the system, the same volume of product is forced out of the reactor loop. Under CSTR conditions, the point at which product flow is recovered is independent of the reactor geometry. However, the top of the third pass is selected such that any air or non-condensable species in the reactor can be conveniently removed at the start of the operation. It is also desirable to ensure that the recovery point is as far as possible from the point where new feedstock is introduced into the system to ensure that the conditions in the reactor have achieved steady state operation and are thus as stable as possible.

The feedstock entering the system via line 15 is not particularly limited and may be any isobutylene-containing flow diagram, such as isobutylene concentrate, dehydro effluent or a typical raff-1 flow. Do. These raw materials are listed in Tables 1, 2 and 3, respectively.

Isobutylene Concentrate ingredient weight% C ₃ s 0.00 I-butane 6.41 n-butane 1.68 1-butene 1.30 I-butene 89.19 trans-2-butene 0.83 cis-2-butene 0.38 1,3-butadiene 0.21

Dehydro effluent ingredient weight% C ₃ 0.38 I-butane 43.07 n-butane 1.29 1-butene 0.81 I-butene 52.58 trans-2-butene 0.98 cis-2-butene 0.69 1,3-butadiene 0.20

Raf-1 ingredient weight% C ₃ 0.57 I-butane 4.42 n-butane 16.15 1-butene 37.22 I-butene 30.01 trans-2-butene 8.38 cis-2-butene 2.27 1,3-butadiene 0.37 MTBE 0.61

For commercial and process economics, the isobutylene content of the feedstock should generally be at least about 30% by weight, with the remainder comprising one or more non-reactive hydrocarbons, preferably alkanes, diluents.

The desired product is a relatively low molecular weight, mid-range vinylidene content PIB product. Therefore, the polyisobutylene leaving the reactor via line 55 should have less than about 10,000 M _N. The speaking generally, produce isobutylene is from about 500 to about 5000 Range M _N, of properly from about 600 to about 4000 Range M _N, preferably of M _N, and more preferably from about 700 to about 3000 range of about 800 to about 2000 M _N range, and ideally should have an M _N of about 900 to 1050 range. By carefully adjusting the various process parameters, it is possible to produce products in which M _N is relatively constant at the desired values, for example 950 or 1000.

In addition, the polydispersity of the relatively low molecular weight mid-range vinylidene content PIB products may be important. The term polydispersity refers to the distribution of molecular weight within a given polymer product and is generally defined as the ratio of the molecular weight of the highest molecular weight molecule to the molecular weight of the lowest molecular weight molecule. Polydispersity can be controlled by carefully maintaining isothermal conditions within constant monomer concentrations and reaction mixtures. Generally speaking, it is desirable to keep the polydispersity as low as possible to improve the quality of the product by lowering the content of undesired relatively low or high molecular weight polyisobutylene in the product. In accordance with the concepts and principles of the present invention, it has been found that the polydispersity of the product can be controlled at about 2.0 or less. Preferably, using the present invention, polydispersity of about 1.65 or less can be achieved. More preferably, the polydispersity can be adjusted to be in the range of about 1.3 to 1.5.

The relatively low molecular weight, mid-range vinylidene content PIB products obtained using the present invention should generally have a terminal (vinylidene) unsaturated content of less than about 70%. That is, less than about 70% of the double bonds remaining in the polymerized product should be at the terminal position. Preferably, the vinylidene content of the relatively low molecular weight mid-range vinylidene content PIB product of the present invention may be less than about 60%, less than about 50%, less than about 40%, less than about 30%, depending on the end use. Can be as low as 20%. Conversely, the beta double bond content of the relatively low molecular weight mid-range vinylidene content PIB products of the present invention is also greater than 30%, greater than 40%, greater than 50%, greater than 60%, 70%, depending on the end use. May be greater than or as high as 80%. In this regard, it should be recognized that vinylidene content may be indirectly related to the conversion rate. In other words, the higher the conversion, the lower the vinylidene content. Moreover, vinylidene content is directly related in the same way as molecular weight. Thus, in each process, a balance may be required between molecular weight, conversion, vinylidene content and beta double bond content.

1 is a schematic illustration of a reactor in the form of a four pass cylindrical tubular heat exchanger useful for carrying out the improved process and for producing the improved mid-range vinylidene of the present invention.

FIG. 2 is a schematic illustration of a reactor in the form of a double pass cylindrical shell and tube heat exchanger useful for carrying out the improved process and producing the improved mid-range vinylidene of the present invention.

Example 1

Using the principles and concepts of the present invention, a reactor, such as the reactor shown in FIG. 1, can be used to prepare the relatively low molecular weight, mid-range vinylidene content PIB product of the present invention. The feedstock may be substantially the same as shown in Table 1 above, and the refrigerant circulated on the shell side of the reactor may be a mixture of 50% methanol and 50% water by weight. The inlet refrigerant temperature may be about 32 degrees Fahrenheit. A 1: 1.3 BF ₃ / methanol complex catalyst can be used to achieve the results described in Table 4 below.

Feedstock flow rate 1.25 gpm Recirculation Flow Rate 35 gpm Feedstock density 5 lb / gal Reaction temperature 60 ℉ Conversion rate 35 wt% Isobutylene Concentration in Feedstock 92 wt% ΔH _reaction 300 BTu / lb μ reaction mixture 4.0 Centipoise = 0.0027 Ib / ftsec Cp of the reaction mixture 0.46 Btu / lb ℉ Reaction effective density 44.9 lb / ft ³ Thermal conductivity 0.07 Btu / hr ft ℉ Total volume of reactor recirculation system 390.2 in ³ Residence time 79.82 seconds Linear velocity in the tube 6.52 ft / sec Reynolds number 2504.4 Surface area of pipe 23.5 ft ² Generated heat 603.8 Btu / min △ T _Im 66.5 ℉ Heat flux 25.6 Btu / min ft ² U 96.1 Btu / min ft ² ℉

Example 2

Using the principles and concepts of the present invention, a full scale reactor, such as reactor 100 shown in FIG. 2, is also used to produce the relatively low molecular weight, mid-range vinylidene content PIB product of the present invention. Can be used. In this case, the reactor 100 is a two-pass cylindrical tubular heat exchanger. Reactor 100 may have, for example, 3880.0375-inch tubes having a wall thickness of 0.035 inches, each providing an inner tube diameter of 0.305 inches. Reactor 100 may be 12 feet long and may have internal baffles and compartments that provide two passes with 194 tubes each. The paths are identified by reference numerals 150 and 151 in FIG. 2, and the 194 tubes of each path are represented by single tube portions 150a and 151a schematically shown in FIG. 2. Suitably, product outlet line 155 may be provided at bottom head 111 of reactor 100. With the exception of the number of passes, the number of tubes per pass, and the location of outlet line 155, reactor 100 of FIG. 2 operates substantially in the same manner as reactor 10 of FIG. 1.

As in Example 1, the feedstock may also be substantially the same as shown in Table 1 above, and the refrigerant circulated on the shell side of the reactor may be a mixture of 50% methanol and 50% water by weight. Intake refrigerant temperature may be about 32 ° F. 1: 1.3 BF ₃ / methanol complex catalyst may be used to achieve the results shown in Table 5 below.

Feedstock flow rate 22 gpm Recirculation Flow Rate 300 gpm Feedstock density 5 lb / gal Reaction temperature 60 ℉ Conversion rate 70 wt% Isobutylene Concentration in Feedstock 89 wt% ΔH _reaction 300 BTu / lb μ reaction mixture 4.0 Centipoise = 0.0027 Ib / ftsec Cp of the reaction mixture 0.46 Btu / lb ℉ Reaction effective density 44.9 lb / ft ³ Thermal conductivity 0.07 Btu / hr ft ℉ Total volume of reactor recirculation system 7794.9 in ³ Residence time 92.03 seconds Linear velocity in the tube 6.79 ft / s Reynolds number 2401.7 Surface area of pipe 457.1 ft ² Generated heat 20559.0 Btu / min △ T _Im 26 ℉ Heat flow rate 45 Btu / min ft ² U 104.3 Btu / min ft ² ℉ Cp of refrigerant 0.86 Btu / lb ℉ Density of refrigerant 7.70 lb / gal Refrigerant flow rate 412.0 gpm ΔT of refrigerant 8.0 ℉

The composition of the product thus obtained is shown in Table 6 below.

Crude polyisobutylene product ingredient weight% C4 31.5 C8 0.07 C12 0.7 C16 0.9 C20 0.7 C24 0.3 Polyisobutylene (PIB) 56.19

As mentioned above, in general the M _N of the product is inversely proportional to the temperature of the reaction. That is, the higher the temperature, in general, the lower the product _N M. In order to explain this phenomenon, the reaction temperature in the reactor 100 was changed in a fixed state of other variables, the results are shown in Table 7 below.

Raw polymer composition (including isobutane and unreacted isobutylene) Molecular Weight Reaction temperature (℉) Raw PIB Composition (wt%) C4 C8 C12 C16 C20 C24 PIB 350 83 19.9 5.0 16.2 11.6 5.2 1.6 40.6 550 75 24.4 0.4 6.2 6.4 3.5 1.6 57.5 750 72 27.9 0.2 2.8 3.2 2.0 0.9 63.1 950 60 31.5 0.07 0.7 0.9 0.7 0.3 65.9 2300 20 64.4 0.004 0.08 0.1 0.1 0.04 35.3

Claims (37)

A polyisobutylene polymer composition comprising polyisobutylene molecules, Wherein a first portion of the polyisobutylene molecules has an alpha position double bond, a second portion of the polyisobutylene molecules has a beta position double bond, The first and second portions together comprise at least 90% of the polyisobutylene molecules of the composition, and the first portion comprises at least 20% to less than 70% of the polyisobutylene molecules of the composition And up to 10% of the polyisobutylene molecules of the composition have tetra-substituted internal double bonds, The polyisobutylene polymer composition, characterized in that the composition has a polydispersity of 2.0 or less. delete The polyisobutylene polymer composition of claim 1, wherein up to 5% of the polyisobutylene molecules of the composition have a tetra-substituted internal double bond. The polyisobutylene polymer composition of claim 1, wherein up to 2% of the polyisobutylene molecules of the composition have a tetra-substituted internal double bond. 2. The polyisobutylene polymer composition of claim 1 having a M _N in the range of 350 to 5000. 6. The polyisobutylene polymer composition of claim 5 having a M _N in the range of 950-1050. The polyisobutylene polymer composition according to claim 1, having a polydispersity of 1.65 or less. The polyisobutylene polymer composition of claim 1, wherein the first portion comprises at least 60% of the molecules of the composition. The polyisobutylene polymer composition of claim 1, wherein the first portion comprises at least 50% of the molecules of the composition. delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete

Images